1. Field of Invention
The present invention relates to an amplifying circuit, and more particularly to an adjustable gain audio power amplifying circuit having an ability of zero-crossing detection.
2. Description of Related Arts
In an audio power amplifying circuit, signal transition always happens to outputted signals of the audio power amplifying circuit during adjusting gains, so that louderspeakers or earphones are readily impacted and produce crackling sounds to bring discomfort to sensitive ears. FIG. 1 shows a simulation waveform of the outputted signals of a conventional audio power amplifying circuit during adjusting the gains, by which it can be seen that an obvious transition happens to the outputted signals.
Thus it is necessary to provide an adjustable gain audio power amplifying circuit able to effectively suppress the crackling sounds caused by adjusting the gains to prevent the outputted signals of the audio power amplifying circuit to transit during adjusting the gains.